Swimmer safety
The Swim Serpentine course will be clearly marked by large buoys and a water safety team will be on hand to assist any swimmers on the day if needed.
All swimmers should be able to complete their chosen distance in full while training in a pool. Swimmers should also practise swimming in the open water before taking on the event.
Open water swimming differs from pool swimming as the water is both open to the elements and is not treated with chlorine. Rainwater, wildlife, warm weather or wildlife are among the many factors that can impact the water in outdoor swimming locations. We therefore carry out regular water quality tests in the Serpentine Lake in the lead-up to Swim Serpentine to ensure we have an accurate and up-to-date understanding of the condition of the water and can give our participants all the information they need.
Water temperature
The weather in the weeks leading up to the swim will determine the water temperature – so be prepared for anything here in the UK!
For important information about water temperature and how it could affect your chosen swim, please look at the tables below.
| Water temperature | Course distance | Wetsuits | Max. time in water* |
|---|---|---|---|
| 15–29°C | Half mile | Optional | 1 hr 10 mins |
| 15–29°C | One mile | Optional | 1 hr 40 mins |
| 15–29°C | Two mile | Optional | 2 hrs 50 mins |
| 15–29°C | Super Six | Optional | 7 hrs** |
| 13.5–14.9°C | Half mile | Optional | 1 hr |
| 13.5–14.9°C | One mile | Optional | 1 hr 10 mins |
| 13.5–14.9°C | Two mile | Optional | 1 hr 30 mins |
| 13.5–14.9°C | Super Six | Optional | 6 hrs** |
Water temperature and reduced distance guidelines
The maximum times in water detailed in the table below are only applicable when the water temperature is below 13.5°C.
| Water temperature | Course distance | Wetsuits | Reduced distance |
|---|---|---|---|
| 13.4°C and below | Half mile | Optional | N/A |
| 13.4°C and below | One mile | Optional | One mile (800m option if swimming slower than 45 mins per mile pace) |
| 13.4°C and below | Two mile | Optional | One mile (800m option if swimming slower than 45 mins per mile pace) |
| 13.4°C and below | Super Six | Optional | Three miles (or 2 hrs 15 mins – whichever is reached first. This is 45 mins per mile pace, so swimmers must pass the second check-in in under 1 hr 30 mins**) |
| 13.5–14.9°C | Two mile | Optional | 1 hr 30 mins |
| 13.5–14.9°C | Super Six | Optional | 6 hrs** |
* Maximum times in water have been determined based on guidance from our medical and water safety team, in line with governing body guidelines and medical evidence around swimming in water of 14°C and below. These times will be used by our on-site safety team to monitor swimmers still in the water and assess the welfare of any swimmer exceeding the maximum time in water. Swimmers may be permitted to continue swimming beyond the maximum time in water providing they are assessed fit to do so by our safety team. Any swimmers showing signs of hypothermia will be asked to exit the water for their own safety and wellbeing.
** Super Six swimmers will check in (while staying in the water) at the end of each lap. The water safety team will have the final say as to whether a swimmer can continue if they appear to be too cold or too tired, or if they are falling behind the maximum time limit.